cAMP-binding activity and cAMp-dependent protein kinase activity from mouse liver will be characterized. The presence of multiple species of these components will be tested by kinetic analysis, thermolability, and ion-exchange chromatography. The properties of these effector molecules will be compared in different adult tissues and as a function of postnatal development. Inbred strains of mice would then be screened for variation in thermolability and electrophoretic variants (indicative of structural genes mutations) and in specific activity (indicative of temporal gene mutations) for both cAMP-binding and protein kinase. The variants found would be subjected to genetic analysis to determine the number of genes involved and linkage group. If such a screen fails to reveal genetic variation, another approach will be tried. cAMP-dependent autophosphorylation and dephosphorylation of the protein kinase regulatory subunit of mouse liver will be studied both as a function of postnatal ontogenesis and to probe the inbred mouse strains for genetic variation in the cAMP effector system. Genetic analysis represents a powerful potential tool for understanding the diversity, function, and interactions fo the cyclic AMP effector molecules.